CN101152998B - Double-reaction area liquefaction catalytic conversion method for producing dimethyl ether with methanol - Google Patents

Abstract

A dual-reaction-zone fluidized catalytic conversion method for methanol to dimethyl ether. Methanol raw material, cooled regenerated catalyst and pre-lifting medium enter the first reaction zone and the second reaction zone in sequence, and are heated at a temperature of 150-500°C and a pressure of 0.1 React under the conditions of MPa～1.0MPa, liquid hourly space velocity 0.5～4 hours ^-1 , mass ratio of catalyst to methanol raw material 1～20, remove the heat from the circulating fluidized bed reactor during the reaction, and separate the reactant flow and the Raw catalyst, in which the reactant flow is separated to obtain the target product dimethyl ether, and the raw catalyst is stripped, regenerated, and cooled in turn for recycling. Compared with the fixed bed, the circulating fluidized bed provides better gas-solid contact, high mass transfer and heat transfer efficiency between gas and solid, thus improving the conversion rate of methanol and the selectivity of dimethyl ether products; and single reaction Compared with the reactor in the zone, the conversion of methanol and the selectivity of the product dimethyl ether can be maximized by controlling the reaction temperature.

Description

A dual reaction zone fluidized catalytic conversion method for methanol to dimethyl ether

technical field

The invention belongs to a method for preparing dimethyl ether by gas-phase catalytic dehydration of methanol, more specifically, a method for preparing dimethyl ether by using a fluidized catalytic conversion method to carry out gas-phase catalytic dehydration of methanol. the

Background technique

Dimethyl ether is a colorless gas or compressed liquid with a slight ethereal odor, non-toxic and non-corrosive, and will not form peroxides when exposed to air for a long time. So far, DME production is modest. As an environmentally friendly fuel, it has only been proposed in recent years, and it has immediately attracted widespread attention from the energy sector all over the world. The physical and chemical properties of dimethyl ether are similar to those of liquefied petroleum gas, and it can become liquid at relatively low pressure. The infrastructure of liquefied gas can be used for dimethyl ether, and long-distance transportation can use oil tanks, tank trucks, or Low-pressure piping that can be dispensed to users with tanks. In addition, DME has a high cetane number (up to 55), making it an ideal diesel alternative fuel. DME will not produce harmful gases such as NO _x and CO during the combustion process, so it is known as a clean fuel in the 21st century. In addition to being used as motor vehicle fuel and civil fuel, DME can be used as a chemical raw material for downstream products such as spray propellants and blowing agents instead of HCFCs. With the increasing demand for dimethyl ether, many countries in the world, especially developed countries, are investing a lot of manpower and financial resources in the research and development of dimethyl ether. DME raw materials come from a wide range of sources and can be obtained from petroleum, natural gas, coal and biomass (such as straw, sorghum stalks, rice bran, etc.). In a word, as my country's petroleum resources are relatively scarce, it is of great significance to use other energy sources to prepare DME as a clean alternative fuel for petroleum products.

Dimethyl ether was first produced by distillation of by-products in high-pressure methanol production. With the progress of methanol synthesis technology, the production technology of methanol dehydration to prepare dimethyl ether has been developed one after another. There are liquid phase method and gas phase method for preparing dimethyl ether by dehydration of methanol. the

The liquid phase method of methanol dehydration to dimethyl ether uses methanol as a raw material to generate methyl hydrogen sulfate under the catalysis of concentrated sulfuric acid, and then reacts methyl hydrogen sulfate with methanol to generate dimethyl ether, and simultaneously generates CO, CO ₂ , H ₂ , CH ₄ , C ₂ H ₄ and other by-products. The method is characterized by low reaction temperature (130-160° C.), selectivity of dimethyl ether and methanol conversion greater than 90%, intermittent or continuous production, relatively small investment, and simple operation. Due to the severe carbonization of methanol by concentrated sulfuric acid, the service life of the catalyst is short. At the same time, the dehydration reaction will produce a large amount of residual acid and waste water, which will seriously pollute the environment. The reaction intermediate methyl hydrogen sulfate is highly toxic and endangers human health. In order to solve these unfavorable factors, CN1111231A discloses a method for synthesizing dimethyl ether by catalytic distillation. The method concentrates the reaction and rectification process in one reactor, and during the reaction process, the product dimethyl ether and methanol are continuously separated, the product has high purity, and no waste acid, waste residue and acid-containing waste water are generated during the process.

The gas-phase method of methanol dehydration to dimethyl ether is to pass methanol vapor through a solid acid catalyst in a fixed-bed catalytic reactor, and a heterogeneous reaction occurs to generate dimethyl ether. The dehydrated mixture is then separated and purified to obtain fuel-grade or aerosol-grade dimethyl ether. The key to this method is the catalyst. The most commonly used catalyst is alumina or aluminum silicate, zeolite or cation exchange resin, and the hydrochloride of metals such as zinc, copper, manganese, and aluminum, and the sulfuric acid of metals such as copper, aluminum, and chromium can also be used. Salt, oxides of metals such as titanium or barium, vanadium thorium compounds, silica gel and aluminum phosphate, etc. The basic characteristics of the catalyst are acidity, high selectivity to the main reaction, less side reactions, and the ability to avoid deep dehydration of dimethyl ether to generate olefins or carbon precipitation. the

To sum up, the existing gas-phase method for producing dimethyl ether by catalytic dehydration of methanol is a feasible method for industrial production, and has been widely used. The problem that needs to be solved at present is how to improve the conversion rate of methanol and the selectivity of dimethyl ether products, and how to reduce investment and operation costs. the

Contents of the invention

The purpose of the present invention is to provide a fluidized catalytic conversion method for methanol to dimethyl ether on the basis of the prior art, so as to improve the conversion rate of methanol raw material and the selectivity of dimethyl ether products. the

Method of the present invention comprises the following steps:

Methanol raw material, cooled regenerated catalyst and pre-lifting medium enter into the first reaction zone and the second reaction zone in sequence, the volume ratio of the second reaction zone to the first reaction zone is 1.5-15:1, at a temperature of 150-500°C Preferably under the conditions of 180-360°C, pressure 0.1MPa-1.0MPa, liquid hourly space velocity 0.5-4.0 hours ^-1 , preferably 0.8-2.0 hours ^-1 , and mass ratio of catalyst to methanol raw material (hereinafter referred to as agent-alcohol ratio) of 1-20 Reaction, remove the heat from the circulating fluidized bed reactor during the reaction, separate the reactant stream and the raw catalyst, wherein the reactant stream is separated to obtain the target product dimethyl ether, and the raw catalyst is stripped, regenerated, and cooled in turn to circulate use.

The content of methanol in the methanol raw material of the present invention is 5-100% by weight, preferably 50-100% by weight, more preferably 90-100% by weight, and may contain a small amount of impurities such as water. The methanol raw material comes from crude methanol produced by gasification and synthesis of various fossil fuels such as natural gas, coal, oil sand, oil shale, petroleum, etc., or methanol from agricultural and forestry products such as wood. In the present invention, methanol can be fed in liquid phase, or can be fed in gas phase after heat exchange with the reaction product. the

The catalyst is an amorphous silica-alumina catalyst or/and a molecular sieve catalyst. the

The amorphous silica-alumina catalyst is γ-Al ₂ O ₃ , or γ-Al ₂ O ₃ modified by one or more than two (including two) elements of copper, zinc, boron, titanium, and phosphorus.

Molecular sieve catalysts are molecular sieves containing or not containing inorganic oxides and clays, preferably molecular sieves containing inorganic oxides and clays, and the molecular sieves are selected from one or more of Y series zeolites, mesoporous zeolites, Beta zeolites, and SAPO molecular sieves (including two), the above-mentioned molecular sieve can be modified by one or more than two (including two) elements in rare earth, phosphorus, group IIA metal elements, and IVB group metal elements, and the group IIA metal elements are preferably Ca Or/and Mg, the Group IVB metal element is preferably Ti or/and Zr. the

The Y series zeolites include Y-type zeolites and their derivatives or modified zeolites, which are selected from one or more than two (including two) mixtures of Y, HY, REY, REHY, USY, and REUSY. the

Medium pore zeolites include ZRP series (rare earth modified), ZSP series (iron modified), ZSM series zeolites and their derivatives or modified zeolites. For a more detailed description of ZRP, see US5,232,675. ZSM series zeolites are selected from ZSM- 5. One or more mixtures of ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, ZSM-38, ZSM-48 and other similar structure zeolites, related to ZSM- 5 See US3,702,886 for a more detailed description. the

The inorganic oxide is selected from one or a mixture of two or more (including two) of alumina, silicon oxide, and amorphous silica-alumina, and the clay is kaolin or/and halloysite. the

The preferred catalyst active component is a mixture of Y zeolite with low rare earth content and low silicon-aluminum ratio and Y zeolite with high rare earth content and high silicon-aluminum ratio. A typical active component is composed of 25-75% by weight of high-silicon Y zeolite _Y1 and 25-75% by weight of high-silicon Y zeolite _Y2 (both based on zeolite weight), wherein the silicon-alumina content of high-silicon Y zeolite _Y1 Ratio is 5-15, rare earth content is 1-10 wt% (calculated as RE ₂ O ₃ ); the silicon-aluminum ratio of high silicon Y zeolite Y ₂ is 16-50, rare earth content is 5-20 wt% (calculated as RE ₂ O ₃ meter).

The pre-lift medium may be water vapor or/and nitrogen. the

The regenerated catalyst is cooled to 150-500° C. through the regenerated catalyst heat-taking section provided with external heat-taking elements, and then enters the first reaction zone through the pre-lifting section. the

The shape of the first reaction zone is generally a cylinder with both upper and lower ends open. In the first reaction zone, as the reaction progresses, the reaction temperature in this zone increases along with the height, so the conversion rate of methanol also increases. Due to its smaller diameter, the upward movement speed of the gas-solid two-phase system is faster, so on the one hand, the conversion rate of methanol is increased due to high temperature, and on the other hand, the subsequent side reaction of the product dimethyl ether to generate hydrocarbons is reduced due to the short reaction time. class and coke. the

Obviously, if the height of the first reaction zone is not limited, although a high conversion rate of methanol will be obtained, it will also increase the dehydration reaction of dimethyl ether to generate olefins. Owing to the high reactivity of olefins, it undergoes a series of catalytic cracking reactions rapidly and eventually leads to the formation of coke. The generated coke will cover the surface of the catalyst or the pores of the catalyst, causing the active center of the catalyst to be lost quickly, seriously affecting the final product distribution and methanol conversion rate. Therefore, the present invention adds a second reaction zone whose volume is much larger than that of the first reaction zone at an appropriate position on the top of the first reaction zone. The shape of the second reaction zone is also generally a cylinder with both upper and lower ends open. , the volume ratio of the second reaction zone to the first reaction zone is 1.5-15:1. the

Controlling the reaction temperature in the second reaction zone is a crucial operational factor for the reaction of methanol dehydration to dimethyl ether. Similar to the heat extraction method in the heat extraction section of the regenerated catalyst, heat extraction elements are also used for heat extraction in the second reaction zone, and high-temperature heat is removed by flowing cold medium. The reaction temperature in the second reaction zone should be controlled at 150-500°C, preferably within the range of 180-360°C. The operating pressure in the second reaction zone should be controlled within 0.1MPa～1.0MPa. The reaction gas and catalyst particles in the second reaction zone constitute a gas-solid two-phase flow system, and its fluidization state can be a fluidization form such as a bubbling bed, a turbulent bed, or a fast bed. The total volume fraction of the solid catalyst particles in the second reaction should account for 0.1-0.45 of the volume of the entire reaction zone. The diameter of the second reaction zone is in the range of 1.5m to 8m, preferably in the range of 3m to 6m. The liquid hourly space velocity in the second reaction zone is 0.5 to 4 hours ⁻¹ , preferably 0.8 to 2.0 hours ⁻¹ . In addition, in order to control the temperature of the second reaction zone more effectively and flexibly.

The reactant flow and catalyst particles in the second reaction zone constitute a gas-solid two-phase flow system, and its fluidization state can be a fluidization form such as a bubbling bed, a turbulent bed, or a fast bed. The total volume share of solid catalyst particles in the reactor should account for 10% to 45% of the entire reactor volume. the

In order to control the temperature of the second reaction zone more effectively and flexibly, one or more catalyst circulation pipelines can be set to take part of the cooled low-temperature catalyst from the reactor to the heat extraction section of the regenerated catalyst, which can significantly reduce the heat absorption of the regenerated catalyst Section and the heat load of the second reaction zone. Of course, according to actual needs, the catalyst circulation pipeline can be closed. The weight of the low-temperature catalyst taken from the reactor to the heat extraction section of the regenerant accounts for 0-20% of the total weight of the catalyst in the reactor. the

The raw catalyst after stripping can also enter the catalyst mixer to mix with the regenerated catalyst. Part of the mixed catalyst enters the regenerator to be burnt, and the other part returns to the first reaction zone and the second reaction zone for recycling after being cooled. The weight of the burnt catalyst entering the regenerator accounts for 0-20% of the total weight of the spent catalyst and the regenerated catalyst. the

The present invention is aimed at the gas-phase method of catalytic dehydration of methanol to produce dimethyl ether, but is not limited thereto, and this method can also be used in the process of producing low-carbon olefins from methanol, which will not be described in detail here. the

The advantage of methanol vapor phase legal system DME provided by the present invention is:

1. Compared with fixed bed, circulating fluidized bed provides better gas-solid contact, high mass transfer and heat transfer efficiency between gas and solid, so it is more conducive to methanol conversion, and the conversion rate of methanol is as high as 95%. the

2. Due to the excellent gas-solid contact, it is easy to control the discharge of heat when taking heat, so the reaction temperature can be flexibly adjusted to obtain ideal product yield and product selectivity. the

3. Due to the use of catalyst cycle regeneration, it is easy to realize continuous and efficient production, increase the processing capacity and increase economic benefits. the

4. Double reaction zones are adopted, and the conversion rate of methanol and the selectivity of the product dimethyl ether can be improved to the greatest extent by controlling the reaction temperature. the

Description of drawings

Fig. 1 is one of the flow diagrams of the double reaction zone fluidized catalytic conversion method for methanol to dimethyl ether provided by the present invention. the

Fig. 2 is the second schematic flow diagram of the dual reaction zone fluidized catalytic conversion method for methanol to dimethyl ether provided by the present invention. the

Detailed ways

The method provided by the present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited thereby. the

The descriptions of each number in the attached drawings are as follows:

1. Distributing plate in the regenerated catalyst heating section; 2. Regenerated catalyst heating section; 3. Pre-lifting section; 4. First reaction zone; 5. Second reaction zone; 6. Settler; 7. Settler inner cyclone Separator; 8. Stripper; 9. Regenerator; 10. Distribution plate at the bottom of regenerator; 11. Cyclone separator in regenerator; 12. Dimethyl ether fractionation tower; 13. Catalyst mixer; 14. Second reaction Heating elements in the area; 15-26 are pipelines. the

Fig. 1 is one of the flow diagrams of the double reaction zone fluidized catalytic conversion method for methanol to dimethyl ether provided by the present invention. the

One of the fluidized catalytic conversion method flowsheets of the methanol-to-dimethyl ether provided by the invention is as follows:

The pre-lift gas from the pipeline 24 enters the regenerated catalyst heat-taking section 2 through the gas distribution plate 1 of the regenerated catalyst heat-taking section, and contacts the regenerated catalyst from the regenerated catalyst pipeline 23, and the cooled regenerated catalyst moves upward together with the pre-lift gas to the pre-lift gas. Lift segment 3. The raw methanol vapor from the pipeline 15 is contacted with the pre-lift gas and the regenerated catalyst in the first reaction zone 4 and the second reaction zone 5 at the top of the pre-lift section 3, and undergoes catalytic dehydration reaction to generate dimethyl ether. In the second reaction zone 5, through one or more heat extraction elements 14 arranged inside the second reaction zone 5, the high-temperature heat is continuously removed from the second reaction zone 5 with a cold medium. The reaction gases and spent catalyst enter the settler cyclone 7 inside the settler 6 . the

The reaction gas discharged from the top of the cyclone separator 7 is sent to the dimethyl ether fractionation column 12 through the pipeline 16 . Unreacted excess methanol is recycled (not shown in the figure), and the liquid phase product at the bottom of the dimethyl ether fractionation tower 12 is extracted through the pipeline 19 as process water for industrial recycling. The hydrocarbons at the top of the dimethyl ether fractionation tower 12 and the upper The dimethyl ether is drawn out of the device through pipeline 17 and pipeline 18 respectively. the

The spent catalyst discharged from the dipleg of the cyclone separator 7 enters the stripper 8 by its own gravity, and the stripped spent catalyst enters the regenerator 9 through the pipeline 20 . The coking air from the pipeline 21 enters the regenerator 9 from the distribution plate 10 at the bottom of the regenerator 9 to burn and react with the carbon deposits on the catalyst to generate CO and CO ₂ gases. In the dilute phase area at the top of the regenerator, the mixed gas of flue gas, N ₂ and O ₂ entrains the regenerated catalyst and passes through the cyclone separator 11 in the regenerator for gas-solid separation. The flue gas is discharged into the flue system through the pipeline 22, and the regenerated catalyst particles are Return to the dense-phase area at the bottom of the regenerator and enter the regenerated catalyst heat-taking section 2 through the pipeline 23 to be cooled and then circulated in the first reaction zone 4 and the second reaction zone 5 in sequence.

Fig. 2 is the second schematic flow diagram of the dual reaction zone fluidized catalytic conversion method for methanol to dimethyl ether provided by the present invention. the

The difference from Fig. 1 is that the raw catalyst after stripping in Fig. 2 first enters the catalyst mixer 13 to mix with the high-temperature regenerated catalyst from the regenerator, and part of the mixed catalyst enters the regenerator for charring, and the other part enters the reaction system middle. the

The fluidized catalytic conversion process flow two of the methanol-to-dimethyl ether provided by the present invention is as follows:

The pre-lift gas from the pipeline 24 enters the regenerated catalyst heat-taking section 2 through the gas distribution plate 1 of the regenerated catalyst heat-taking section, and contacts the regenerated catalyst from the regenerated catalyst pipeline 23, and the cooled regenerated catalyst moves upward together with the pre-lift gas to the pre-lift gas. Lift segment 3. The raw methanol vapor from the pipeline 15 is contacted with the pre-lift gas and the regenerated catalyst in the first reaction zone 4 and the second reaction zone 5 at the top of the pre-lift section 3, and undergoes catalytic dehydration reaction to generate dimethyl ether. In the second reaction zone 5, through one or more heat extraction elements 14 arranged inside the second reaction zone 5, the high-temperature heat is continuously removed from the second reaction zone 5 with a cold medium. The reaction gases and spent catalyst enter the settler cyclone 7 inside the settler 6 . the

The reaction gas discharged from the top of the cyclone separator 7 is sent to the dimethyl ether fractionation column 12 through the pipeline 16 . Unreacted excess methanol is recycled (not shown in the figure), and the liquid phase product at the bottom of the dimethyl ether fractionation tower 12 is extracted through the pipeline 19 as process water for industrial recycling. The non-condensable gas at the top of the dimethyl ether fractionation tower 12 is and the upper part of dimethyl ether are drawn out of the device through pipeline 17 and pipeline 18 respectively. the

The raw catalyst discharged from the dipleg of the cyclone separator 7 enters the stripper 8 by its own gravity, and the raw catalyst after stripping enters the catalyst mixer 13 through the pipeline 20 to mix with the high-temperature regenerated catalyst from the pipeline 26, and the mixed catalyst A part enters the regenerator 9 through the pipeline 25, and the other part then enters the regenerated catalyst heat-taking section 2 through the pipeline 23, and after being cooled, it is recycled in the first reaction zone 4 and the second reaction zone 5 successively. the

The coking air from the pipeline 21 enters the regenerator 9 from the distribution plate 10 at the bottom of the regenerator 9 to burn and react with the carbon deposits on the catalyst to generate CO and CO ₂ gases. In the dilute phase area at the top of the regenerator, the mixed gas of flue gas, N ₂ and O ₂ entrains the regenerated catalyst and passes through the cyclone separator 11 in the regenerator for gas-solid separation. The flue gas is discharged into the flue system through the pipeline 22, and the regenerated catalyst particles are Return to the dense phase zone at the bottom of the regenerator and enter the catalyst mixer 13 through line 26.

The following examples will further illustrate the present invention, but do not limit the present invention thereby. the

Each of the following examples was carried out by simulating different reaction zones on two medium-sized fixed fluidized bed reactors with different volumes, and the volume ratio of the second reaction zone to the first reaction zone was 4.5:1. The methanol raw material used in the test is industrial methanol, and the methanol content is greater than 93% by weight. the

The preparation method of catalyst A used in the examples is as follows: the high-silica Y zeolite Y ₁ used in the preparation of the catalyst is prepared by hydrothermal treatment and rare earth ion exchange with _NH4Y , and its silicon _- aluminum ratio is _6.3 . The rare earth content is 4% by weight; the high silicon Y zeolite Y ₂ is prepared by NaY through _SiCl4 gas phase treatment and rare earth ion exchange, its silicon-aluminum ratio is 18, and the rare earth content is 14% by RE ₂ O ₃ %. The weight ratio of high silica Y zeolite Y ₁ to high silica Y zeolite Y ₂ was 1.67. With 4300 grams of decationized water, 969 grams of polyhydrate kaolin (product of China Kaolin Company, 73% by weight) is beaten, and then 781 grams of pseudo-boehmite (product of Shandong Zibo Aluminum Stone Factory, 64% by weight of solid content) and 144ml of hydrochloric acid (concentration 30%, specific gravity 1.56) was stirred evenly, left to age at 60°C for 1 hour, and the pH value was kept at 2 to 4, and then dropped to normal temperature, then added the pre-prepared solution containing 500g zeolite Y ₁ (dry basis), A zeolite slurry of 300 g of zeolite Y ₂ (dry basis) and 200 g of chemical water was stirred evenly, spray-dried, and free Na ⁺ was washed away to obtain catalyst A. The properties of the catalyst are listed in Table 1.

Example 1

Methanol raw material, regenerated catalyst A cooled to 400°C by the regenerated catalyst heat extraction section, and water vapor enter the pre-lifting section, the first reaction zone, and the second reaction zone in sequence. Reaction under the conditions of hourly space velocity 4 hours ^-1 , agent-alcohol ratio 2, the weight of low-temperature catalyst taken from the second reaction zone to the heat extraction section of the regenerant during the reaction accounts for 15% of the total weight of the catalyst in the reactor, and the separation reaction The stream and the raw catalyst, wherein the reactant stream is separated to obtain the target product dimethyl ether, and the raw catalyst is stripped and regenerated in turn, and then enters the regenerated catalyst to take the heat section to cool and return to the reaction system for recycling.

The operating conditions and product distribution are listed in Table 2. As can be seen from Table 2, the conversion rate of methanol is as high as 100.00%, the selectivity of dimethyl ether is 83.15%, and the yield of dimethyl ether is 83.15% by weight. the

Comparative example 1

This comparative example illustrates the situation in which methanol raw material is used to produce dimethyl ether in a fixed bed. The catalyst used has the same composition as catalyst A, but the shape and size are different. The rest of the operating conditions are the same as in Example 1. the

The operating conditions and product distribution are listed in Table 2. As can be seen from Table 2, the conversion rate of methanol is only 74.49%, the selectivity of dimethyl ether is 94.32%, and the yield of dimethyl ether is 70.26% by weight. the

Comparative example 2

This comparative example illustrates the situation in which methanol feedstock is used to produce dimethyl ether in a circulating fluidized bed reactor with only one reaction zone. Catalyst used, operating condition are all identical with embodiment 1. the

Methanol raw material, regenerated catalyst A cooled to 400°C by the regenerated catalyst heat extraction section, and water vapor enter the pre-lifting section and the circulating fluidized bed reactor in sequence. Reaction under the condition of hour ^-1 , agent-alcohol ratio 2, the weight of the low-temperature catalyst taken from the reactor to the regenerator heating section during the reaction accounts for 15% of the total weight of the catalyst in the reactor, and the reactant flow is separated from the raw catalyst , wherein the reactant flow is separated to obtain the target product dimethyl ether, and the raw catalyst is stripped and regenerated in turn, and then enters the regenerated catalyst to take the hot section to cool, and then returns to the reaction system for recycling.

The operating conditions and product distribution are listed in Table 2. As can be seen from Table 2, the conversion rate of methanol is as high as 83.93%, the selectivity of dimethyl ether is 84.10%, and the yield of dimethyl ether is 70.59% by weight. the

Example 2

Methanol raw material, the regenerated catalyst A cooled to 350°C by the regenerated catalyst heat extraction section and water vapor enter the pre-lifting section, the first reaction zone, and the second reaction zone in sequence. Reaction under the conditions of liquid hourly space velocity 2.5 hours ^-1 and agent-alcohol ratio of 10, no low-temperature catalyst was taken from the second reaction zone to the heat extraction section of the regenerant during the reaction, that is, there was no catalyst circulation in the second reaction zone, and the separation reaction The stream and the raw catalyst, wherein the reactant stream is separated to obtain the target product dimethyl ether, the raw catalyst is stripped in turn and mixed with the high-temperature regenerated catalyst, and 40% by weight of the mixed catalyst enters the regenerator and burns, and the other part is Enter the regenerated catalyst to take the heat section and return to the reaction system for recycling after cooling.

The operating conditions and product distribution are listed in Table 3. It can be seen from Table 3 that the conversion rate of methanol is as high as 100.00%, the selectivity of dimethyl ether is 85.80%, and the yield of dimethyl ether is 85.80% by weight. the

Example 3

Methanol feedstock, regenerated catalyst A cooled to 200°C and water vapor enter the pre-lifting section, the first reaction zone, and the second reaction zone in sequence, and are heated at a pressure of 0.11 MPa (gauge pressure), a temperature of 200°C, and a liquid hourly space velocity of 0.5 hours ^-1 , react under the condition of agent-to-alcohol ratio of 18, in the reaction process, the low-temperature catalyst is not taken away from the second reaction zone to the regenerant heating section, that is, there is no catalyst circulation in the second reaction zone, and the reactant flow is separated from the catalyst to be born, wherein The reactant stream is separated to obtain the target product dimethyl ether, and the raw catalyst is successively stripped and regenerated, and then enters the regenerated catalyst to take the hot section to cool, and then returns to the reaction system for recycling.

The operating conditions and product distribution are listed in Table 3. It can be seen from Table 3 that the conversion rate of methanol is as high as 100.00%, the selectivity of dimethyl ether is 87.09%, and the yield of dimethyl ether is 87.09% by weight. the

Table 1

Zeolite type Y ₁ +Y ₂ Chemical composition, wt% Alumina 25.0 sodium oxide 0.3 iron oxide 1.0 Apparent density, kg/m ³ 730 Pore volume, ml/g 0.42 Specific surface area, m ² /g 286 Wear index, weight %/h ^-1 2.0 Sieve composition, wt% 0～40μm 18.5 40～80μm 50.6 ＞80μm 30.9

Table 2

Example 1 Comparative example 1 Comparative example 2 operating conditions Pressure (gauge pressure), MPa 0.11 0.11 0.11 temperature, ℃ 400 400 400 Airspeed, h ^-1 4.0 4.0 4.0 Dosage alcohol ratio 2 2 2 Product distribution, weight % Dimethyl ether 54.37 37.36 45.18 hydrocarbon 11.01 2.25 8.54 coke 0.94 0.22 0.68 water 33.68 34.66 29.53 Methanol 0.00 25.51 16.07 Total 100 100 100 Conversion rate of methanol, % 100.00 74.49 83.93 Selectivity of dimethyl ether, % 83.15 94.32 84.10

table 3

Example 2 Example 3 operating conditions Pressure (gauge pressure), MPa 0.11 0.11

temperature, ℃ 350 250 Airspeed, h ^-1 2.5 0.5 Dosage alcohol ratio 10 18 Product distribution, weight % Dimethyl ether 58.42 56.96 hydrocarbon 9.67 8.44 coke 0.81 0.72 water 31.1 33.88 Methanol 0.00 0.00 Total 100 100 Conversion rate of methanol, % 100.00 100.00 Selectivity of dimethyl ether, % 85.80 87.09

Claims (16)

1. the double-reaction area liquefaction catalytic conversion method of a preparing dimethyl ether from methanol is characterized in that this method comprises the following steps:

Methanol feedstock and cooled regenerated catalyst and the pre-medium that promotes enter first reaction zone, second reaction zone successively, second reaction zone was 1.5～15: 1 with the ratio of the volume of first reaction zone, 150～500 ℃ of temperature, pressure 0.1MPa～1.0MPa, liquid hourly space velocity 0.5～4 hour ^-1, catalyzer and methanol feedstock the condition of mass ratio 1～20 under react, in reaction process, remove heat from circulating fluid bed reactor, separating reaction logistics and reclaimable catalyst, wherein reactant flow obtains purpose product dme through separation, and reclaimable catalyst recycles after stripping, regeneration, cooling successively.

2. according to the method for claim 1, the content that it is characterized in that methyl alcohol in the described methanol feedstock is 5～100 heavy %.

3. according to the method for claim 1, the content that it is characterized in that methyl alcohol in the described methanol feedstock is 50～100 heavy %.

4. according to the method for claim 1, the content that it is characterized in that methyl alcohol in the described methanol feedstock is 90～100 heavy %.

5. according to the method for claim 1, it is characterized in that described catalyzer amorphous silicon aluminium catalyzer is or/and molecular sieve catalyst.

6. according to the method for claim 5, it is characterized in that described amorphous silicon aluminium catalyzer is γ-Al ₂O ₃, or one or more the element modified γ-Al in copper, zinc, boron, titanium, phosphorus ₂O ₃

7. according to the method for claim 5, it is characterized in that described molecular sieve catalyst is the molecular sieve that contains or do not contain inorganic oxide and clay.

8. according to the method for claim 7, it is characterized in that one or more the mixture of described molecular screening in Y series zeolite, mesopore zeolite, Beta zeolite, SAPO molecular sieve, above-mentioned molecular sieve can be in rare earth, phosphorus, IIA family metallic element, IVB family metallic element one or more are element modified, described IIA family metallic element is Ca or/and Mg, and described IVB family metallic element is that Ti is or/and Zr.

9. according to the method for claim 8, it is characterized in that described Y series zeolite is selected from one or more the mixture among Y, HY, REY, REHY, USY, the REUSY.

10. according to the method for claim 8, it is characterized in that described mesopore zeolite comprises ZRP series, ZSP series, ZSM series zeolite and derives or modified zeolite.

11. according to the method for claim 7, it is characterized in that described inorganic oxide is selected from one or more the mixture in aluminum oxide, silicon oxide, the amorphous silicon aluminium, clay is that kaolin is or/and halloysite.

12., it is characterized in that described pre-lifting medium can be that water vapor is or/and nitrogen according to the method for claim 1.

13., it is characterized in that described regenerated catalyst is cooled to 150～500 ℃ through the regenerated catalyst heat-obtaining section that the outside heat removing element is set according to the method for claim 1.

14., it is characterized in that constantly removing heat with cold medium from second reaction zone by being arranged on one or more outside heat removing elements of the second reaction zone inside according to the method for claim 1.

15. method according to claim 1, it is characterized in that being provided with one or more catalyst recycle line and take the cooled low temperature catalyst of part away to regenerated catalyst heat-obtaining section, take away to the low temperature catalyst weight of regenerator heat-obtaining section from reactor and account for 0～20% of catalyst in reactor gross weight from second reaction zone.

16. method according to claim 1, it is characterized in that reclaimable catalyst behind the stripping is introduced into the catalyst mix device and mixes with regenerated catalyst, a mixed catalyzer part enters revivifier and burns, another part then after cooling off Returning reacting system recycle.

Images